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    <title>Document</title>
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<body>
    <form id='form'>
        用户名：<input type="text" name="uname"><br>
        密码：<input type="text" name="upwd"><br>
        <input type="submit" value="提交">
    </form>
    <script>
        var form = document.querySelector('#form');
        form.onsubmit = function (e) {
            e.preventDefault();
            var fm = new FormData(form);
            var xhr = new XMLHttpRequest();
            xhr.open('POST', 'http://www.liulongbin.top:3006/api/formdata');
            xhr.send(fm);
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4 && xhr.status == 200) {
                    console.log(JSON.parse(xhr.responseText));
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    </script>
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